This invention relates to a method of volumetric subdivision of conveyed bar-shaped material such as bar steel or billets, wherein the cross-section of the bar-shaped material is measured and in accordance with this measured value a length stop is adjusted by means of a computer in such a way as to enable a length of blank material having a predetermined value to be severed from the stock.
The invention also relates to an apparatus for the application of this method.
A method of this kind as well as apparatus for the application thereof is disclosed in German Patent 316 276. According to this West German Patent the bar-shaped material or stock which is in course of being conveyed is conducted through an annular measuring coil surrounding the stock, the coil being part of an electric circuit and its impedance varying in relation with the cross section of the material passing therethrough. This variation is picked up as a measure of the cross section and processed by means of a computer in such a way that a length stop is automatically adjusted in relation to the size of the cross section so that ultimately a portion of the computer-determined length can be severed from the material by means of a shearing blade.
This kind of volumetric subdivision of the material is of considerable importance for the subsequent working of the severed portion whenever such further working or treatment requires that the severed portion or blank should precisely fill a given volume. This is the case, for example, in non-cutting deformation or shaping processes, such as drop forging, the aim being here not only that a given die cavity should be completely filled by the material but also that there should be no burr or flash or at any rate that this should be confined to a minimum. A laterally squeezed-out flash, or burr, will, as a general rule, not only represent a loss of material, but also require one or more working passes for its elimination. Further, it will entail heavier wear in the region of the edge of the die so that the desired shape cannot be achieved with the required degree of accuracy. In practice it is customary to have an average 8 to 9% excess volume for the blank in order to make sure that the die is completely filled. According to the above mentioned German Pat. No. 316 276 this excess can be cut down to as little as .+-.2%.
Other known methods rely on the weight/volume ratio of the material and provide for the initial cutting of a sample blank, of which the weight is ascertained, whereupon the subsequent blanks are cut to that length which corresponds to a blank weight which is capable of filling a predetermined volume. However, here, too, tolerances of the order of .+-.0.5% must be permitted. Examples of this kind of method are described in GL-PS No. 96 041 and German Laid-Open Specification No. 2,259,950.